M4.2 Earthquake 79 km SW of Ishigaki, Japan — August 23, 2021
2021-08-23 19:19:23 UTC (2021-08-23) · approx. 3:19 AM UTC+8 local
On August 23, 2021 at 19:19 UTC, a magnitude 4.2 shallow crustal earthquake struck 79 km SW of Ishigaki, Japan, at a depth of 30.5 km and coordinates 23.8243°, 123.6157°.
Physical scale: An earthquake of magnitude 4.2 releases seismic energy equivalent to roughly 30 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 476 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
123.6157°E
Technical Information
Common Questions
How strong was the magnitude 4.2 earthquake near Ishigaki, Japan?
The magnitude 4.2 earthquake that struck 79 km SW of Ishigaki, Japan on August 23, 2021 at 19:19 UTC had a depth of 30.5 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.2 earthquakes can continue for several days and gradually diminish over time.
Actions
Location
Understanding This Data
Magnitude 4.2 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000f73a). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, August 23, 2021). M4.2 Earthquake 79 km SW of Ishigaki, Japan — August 23, 2021. Retrieved November 2, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000f73a/